1. Field of the Invention
The present invention relates to a rolling bearing apparatus.
2. Description of Related Art
For various machine tools, there has recently been a demand to increase the speed of a main spindle in order to improve machining efficiency and productivity. When the main spindle rotates at high speed, an increased amount of heat is generated in a bearing that supports the main spindle. Therefore, such a bearing needs means for suppressing increase in temperature of the main spindle.
As the means for suppressing increase in temperature of the bearing, a method for cooling the bearing in operation is available. For this method, for example, a cooling structure described in Japanese Patent Application Publication No. 2014-62616 (JP 2014-62616 A) is available. This cooling structure supplies the bearing with compressed air in addition to oil air, thereby suppressing increase in temperature of the bearing.
In the cooling structure for a bearing apparatus described in JP 2014-62616 A, a first nozzle through which the oil air is injected is provided in an outer-ring spacer. A unit that allows oil air to be generated is provided outside the bearing. A channel that connects this mechanism to the first nozzle is provided in a housing for the bearing or the like.
In the cooling structure described in JP 2014-62616 A, a second nozzle through which the compressed air is injected is further provided in the outer-ring spacer. A unit for generating the compressed air is provided outside the bearing. A channel that connects this mechanism to the second nozzle is provided in the housing for the bearing or the like.
As described above, the related art described in JP 2014-62616 is provided with the configuration for feeding the compressed air outside the bearing to the inside of the bearing in order to enhance a cooling effect for the bearing, besides the configuration for lubrication with the oil air that is needed to lubricate the bearing. Thus, the conventional bearing apparatus generally has a complicated structure. The necessity of cooling of the bearing is not limited to the machine tool as described above but is also present in other types of equipment in which a shaft rotates at high speed.